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no start when cold -32 f 740 700 1990

posted by  pilebuck on  Mon Feb 21 09:32 CST 2005
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last visit: Wed Aug 5 09:11 CST 2009
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need help, this car recently began to not start only when very cold, take the car inside or wait for the temperature to rise and it will start. It has the regina engine control system. I have replaced the coil and swapped out the module attached to the coil but to no avail.
It is getting fuel just no spark when it is cold. This car has 354,000 miles I have never run across this kind of problem with volvos
any help would be greatly appreciated, thank you








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    (edited reply) no start when cold -32 f 740 700 1990

    uid 18083's pic
    posted by  lucid on  Tue Feb 22 08:53 CST 2005
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    last visit: Fri Oct 24 12:31 CST 2014
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    It is getting fuel just no spark when it is cold.

    Are you sure about the fuel? The FI system is designed to pump no fuel until the Rex Ignition CU sends the Regina ECU a "Spark OK" signal. (Rex pin 17 to Regina pin 1.) Don't be misled by the pump running with Key ON. That's not the same circuit as when cranking/running.

    I also agree that anything you can do to improve cranking voltage will be worthwhile, along with replacing the RPM sender as a mileage-related preventive measure.

    Maybe try some hair dryer heat down behind the block to see if it affects the RPM sender? Probably better access from the right side.
    --
    Bruce Young
    '93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.








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      (edited reply) no start when cold -32 f 740 700 1990

      posted by  pilebuck on  Tue Feb 22 09:38 CST 2005
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      last visit: Wed Aug 5 09:11 CST 2009
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      thanks for the info, as for the fuel I am just going on the smell in the engine compartment after a no start. Where does the rex module get it's trigger info from, would this be the impulse sensor rex pin 23,10,11? or is the rpm sensor the same? Is the trigger information supplied to the rex coil from pin 6 or 16? thank you very much








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        no start when cold -32 f 740 700 1990

        uid 18083's pic
        posted by  lucid on  Tue Feb 22 10:26 CST 2005
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        last visit: Fri Oct 24 12:31 CST 2014
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        Right, Rex trigger inputs are 23,10,11 from RPM Sensor (Greenbook term).
        Coil trigger looks like Rex 16.

        Rex 6 and 5 are +12V inputs.
        6 is unfused Blue wiring, and is common to OBD socket 4 and Amp/coil A of ABC group. B is ground, C (R-W) is Tach impulse.
        5 is Brown from fuse #1 and is common to Regina ECU 4 (W) and and Fuel relay 30 (BN).
        --
        Bruce Young
        '93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.








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          no start when cold -32 f 740 700 1990

          posted by  pilebuck on  Tue Feb 22 10:45 CST 2005
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          last visit: Wed Aug 5 09:11 CST 2009
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          thank you very much, Bruce exept for any interior rex or regina ecu problems it looks like it could only be the rpm sensor, I measured the trigger voltage measured to ground it was 0.1 volts this has to be out of range. You have been a great help thank you








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            no start when cold -32 f 740 700 1990

            uid 18083's pic
            posted by  lucid on  Tue Feb 22 11:01 CST 2005
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            last visit: Fri Oct 24 12:31 CST 2014
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            Thank you for the feedback. Most times we never know if we helped or not.
            --
            Bruce Young
            '93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.








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    no start when cold -32 f 740 700 1990

    posted by  Sumerduckman on  Tue Feb 22 07:30 CST 2005
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    last visit: Tue Aug 21 11:31 CST 2007
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    Check, or have someone check the condition of the battery and cables. If the voltage falls below 9.6v while cranking, she will not fire. When it gets that cold, they can take a lot of juice to turn over.

    And yes, the Regina's have an rpm sensor, in the same spot as the LH's at the top of the bellhousing. If it has not been replaced in a while, it couldn't hurt. They are not that expensive.
    --
    '94 940 na Regina 150k, '86 240 180k, 93 Camry 5sp 245k, 88 Toy 4wd 166k








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    no start when cold -32 f 740 700 1990

    posted by  darmstrong on  Mon Feb 21 14:25 CST 2005
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    last visit: Sat Sep 13 12:21 CST 2014
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    I'm not sure I've seen a loss of spark due strictly to temperature; usually cold start issues are from too lean a fuel mixture.

    I don't know the 740 w/Regina; does it have a crank position sensor? It seems to be implicated in a lot of starting issues.



    --
    David Armstrong - '86 240(350k km?), '93 940T(270k km), '89 240(parts source for others) near Toronto







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